HttpCachePolicy.AppendCacheExtension Method (String)


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Appends the specified text to the Cache-Control HTTP header.

Namespace:   System.Web
Assembly:  System.Web (in System.Web.dll)

public void AppendCacheExtension(
	string extension


Type: System.String

The text to append to the Cache-Control header.

Exception Condition

extension is null.

If the browser does not recognize cache control directives or extensions, the browser must ignore the unrecognized terms. For more information, see RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1, available on the World Wide Web Consortium (W3C) Web site.

AppendCacheExtension is introduced in the .NET Framework version 3.5. For more information, see .NET Framework Versions and Dependencies.

The following code example demonstrates the use of a cache-control extension supported by Internet Explorer. The server is indicating to the browser that the content will not change for one hour (pre-check=3600) and instructs it to retrieve the content directly from the local cache. However, if the content is modified by the server and the page is requested by the user within a fifteen-minute (post-check= 900) to one-hour period, the browser displays the information found in the local cache but also performs a background check and optional fetch of the new content on the server.


.NET Framework
Available since 1.1
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